Drying chamber



Nova 19, 194%. w, s, BOWEN DRYING CHAMBER Filed June 1, 1958 l| W M m w M Patented Nov. 19, 1940 UNITEDSTATES PATENT OFFICE" William Spencer Bowen, Westflcld, N. J.

Application June 1, 1938, Serial No. 211,119

13 Claims.

the particles while they are in a finely divided state, so that the suspended liquid may be readily evaporated and the solid material obtained in the form of a fine powder.

In certain of these processes the fluid suspension is sprayed in at the top of a drying chamber and a, whirling column of air is directed through it which mixes with the finely divided suspended material to form a vortex which moves downwardly in a helical path. It has been found, however, that the vortex tends to spread out as it moves downwardly in the drying chamber and some of the suspended material is thrown off on the wall of the drying chamber before the moisture has been completely removed, thus forming an undesirable layer of solid material on the surfaces of the drying chamber. The spreading out of the vortex furthermore, gives rise to numerous dead spaces within the chamber in which the dried material is able to collect.

An attempt has been made in other constructions to confine the vortex to the central portion of the drying chamber by feeding in the air tangentially. When thus fed, however, the air forms a spirally rotating column which, a1-

.) though it prevents the finely divided fluid from being thrown off on thesurfaces of the drying chamber, does not mingle with the fluid to any great extent so that disproportionately large 'quantities of air are required to obtain a product having the desired dryness.

An object of the invention accordingly, is to provide a drying chamber for rapidly and effectively reducing the moisture content of atomized solids, in which the finely divided material is confined centrally in the chamber for'its entire length.

A further object of the invention is to provide a drying chamber of the above character from which the dried solids may be removed without substantially disturbing the vortex in the central portion thereof.

Another object of the invention is to provide a drying chamber of the above character having an exhaust outlet of small dimensions for removing the dried solid without'breaking up the vortex,

In a preferred embodiment of the invention, atomized fluid is fed in at the top of the drying chamber and a spirally rotating column of heated air is fed downwardl through the atomized fluid forming a vortex in which the air is thoroughly mixed with the fluid particles. Heated air is then fed in about the periphery of the drying chamber in such fashion that it has both radial and tangential components, so that while it is directed neither radially nor tangentially into the vortex, the incoming air gets a circulatory motion and, at the same time, penetrates to the center of the chamber. The movement of the vortex gives it'an additional component so that it tends to move downwardly and the moisture laden particles are continually maintained in contact with heated air. The radial component of the incoming heated air tends to confine the vortex and prevent it from spreading out, so that it is kept centrally in the drying chamber. Thus the sprayed material is kept away from the walls of the drying chamber and is maintained in suspension until substantially all of the moisture has been removed.

Cold air is fed into the lower portion of the drying chamber in the same manner as described above for the heated air, and it serves to brine the temperature of the product down to the point where it may be conveniently exhausted. The incoming cold air also has a radial component which aids in concentrating the vortex in the central portion of the drying chamber so that there are no dead spaces within which the dried product may collect. When the material has been completely dried, it is exhausted through a cone-shaped outlet which tends to maintain the vortex in the central portion f the chamber. This outlet preferably is surrounded by a scroll-shaped elbow which directs the air-suspended dried product to an outlet duct without disturbing the whirlin motion of the vortex to any appreciable extent. The scroll elbow obviously occupies only a small amount of space, which is of great advantage where only a limited space is available. If there is sufficient space, however, an elongated funnelshaped outlet may be used which will also maintain the flow of air in the vortex up to the point where the material is exhausted from the apparatus.

This invention, therefore, provides a drying chamber in which the sweeping action of the vortex throughout all portions of the chamber rapidly and effectively removes moisture from the suspended solids while keeping them away from its walls. It further provides an improved exhaust outlet construction, by means of which all of the dried material may be removed fromline 4-4 on Figure 2 and looking in the direction of the arrows;

Figure 5 is a partial view in elevation showing a modified form of outlet for exhausting the dried material without disturbing the vortex in the chamber. In the embodiment shown in Figure 1, the drying chamber is formed in three sections, l0, II and I2, which are secured coaxially to one another by suitable flanges and bolts. The section I 0 is cylindrical in shape and is surrounded by a scroll casing l3 which is provided with an inlet I4 through which heated air may be supplied to the chamber. About the periphery of the section III, atapered slot I5 is formed through which the heated air is adapted to be uniformly admitted to the drying chamber from the scroll casing iii. The narrow portion of the slot is formed near the portion of the scroll casing l3 which has the greatest radius, and the slot diverges substantially linearly so that its widest portion is adjacent the part of the scroll casing of least radius. With this construction, the air inlet area is small where the pressure is high, and is large where the pressure is low, so that air is admitted substantially uniformly about the periphery of the section III.

on the upper surface of the section III, a. scroll I casing l6 is-formed in which the atomizer I1 is adapted to be secured and to which heated air is supplied from the inlet duct 20.. The atomizer l'l extends downwardly into a converging passage l8 which terminates in an annular outlet l9 from which heated air maybe directed downwardly through the atomized fluid. It will be noted that the passage of air through the outlet l9 from the scroll casing It provides a spirally rotating downwardly moving column of air which is directed through the finely divided fluid. The fluid is carried downwardly along with the heated air, thus forming a vortex of rapidly moving airand 1 solid particles.

The air directed into the chamber through the tapered slot l5 has a radial component which tends to prevent the central vortex from spreading to the walls of the chamber and, at the same time, it has a tangential component sotha-t it continues to move in a spiral path within the 5 chamber. Thus the vortex comprising a mixture of heated air and suspended particles is almost exclusively confined in the central portion of the drying chamber, so that the moisture-laden solid particles are 70 oil. on its surfaces.

The second section II which is mounted coaxially with the section III is provided with a similar scroll casing 2i to which cold air is supplied through an inlet 22. A tapered slot 23 is formed 75 in the periphery of the section II, its narrowest prevented from being thrown portion being adjacent the portion of the scroll casing of greatest radius, and its widest portion being adjacent the portion of the scroll casing of least radius. As pointed out above'in connection with the slot l5, this tapered slot allows the cold air to enter the drying chamber substantially uni-.

handled after being exhausted from the dryingchamber.

, The third section I 2 comprises a short coneshaped member secured coaxially to the section Ii and surrounded by a scoll casing 24, which is provided with an outlet 25 from which the dry air-suspended product may be exhausted. In the bottom of the scroll casing 24 a cone-shaped member 26 is formectwhose vortex extends 'substantially into, and centrally of, an outlet opening 21 formed in the bottom of the cone l2. The conical shape of the section I 2 maintains the vortex in the central portion of thedrying chamber and, at the same time, directs it to the scroll casing 24 so that the dried material can be readily exhausted without disturbing the air flow in the vortex by any substantial amount.

The same result may be secured by the modification shown in Figure 5, in which a member 28 is secured to the section II which forms a downwardlyextending passage converging to an elbow portion 29, from which the dried material may be exhausted through an outlet 30. This construction also enables the dried material to be exhausted from the chamber without breaking up the vortex, although it increases the height of the drying chamber to someextent.

The invention provides an improved drying chamber in which the atomized solids are mixed with heated air in a vortex which is confined to the central portion of the chamber, thus preventing the solid partlcles from being thrown oil against the walls of the chamber before the moisture has been completely removed from them,,

and preventing the collection of dried material in dead spaces within the chamber. It furthermore provides an improved exhaust construction by means of which the dried solids may be readily and efl'eotively removed from the drying chamber without breaking up the fluid flow in the vortex.

It will be evident that numerous changes in formand detail are possible within the scope of the invention and /although a specific embodi-' ment has been described above, it is not intended to be limited in any waythereby, except as deflned in the following claims. g

I claim:

1. A drying apparatus for removing moisture from atomized particles comprising a chamber having a slot therein, means to introduce atomized fluid to the chamber, means forming an opening in the chamber-for directing an axially moving and rotating column ofair over the moisture-laden particles to form a vortex, and a scroll casing on the chamber cooperating with .the said slot for directing air into the chamber inwardly and oft a tangent of the periphery of the chamber, for confining the vortex centrally therein and spaced from the chamber walls.

2. A drying apparatus for removing moisture from atomized particles comprising a chamber having a tapered slot therein. means to introduce fluid to the chamber, means forming an opening in the chamber for directing an axially moving and rotating column of air over the moistureladen particles to form a vortex, and a scroll casing on the chamber over the slot, the narrow portion of the slot being adjacent the portion of the scroll casing of greatest radius, and the wide portion of the slot being adjacent the portion of the scroll casing of least radius, for directing air' means in the bottom of the chamber forming a converging outlet, and a scroll casing over the outlet for exhausting the dried particles without substantially disturbing the vortex in the chamher.

4. In a drying apparatus for removing moisture from atomized particles, the combination of a casing, means in the casing forming a tapered slot extending substantially around the periphery thereof, and means for introducing air inwardly and off a tangent of the periphery of the casing through the slot into the casing.

5. In a drying apparatus for removing moisture from atomized particles, the combination of a casing, means in the casing forming a tapered slot therein extending substantially around the periphery thereof, and a scroll casing over the slot for introducing air inwardly and oil a tangent of the periphery of the casing into the casing.

6. In a drying apparatus for removing moisture from atomized particles, the combination of a casing, means forming a tapered slot in the casing, and a scroll casing over the slot, the narrow portion of the slot being adjacent the portion of the scroll casing of greatest radius, and the wide portion of the slot being adjacent the portion of the scroll casing of least radius.

7. In a drying apparatus for removing moisture from atomized particles, the combination of ,a casing having a lower portion converging to an outlet, means to supply air to the casing to form a vortex, and scroll means cooperating with and coaxial to the said outlet for exhausting the air and dried material outwardly from the casing without substantially disturbing the vortex therein.

8. In a drying apparatus for removing moisture from atomized particles, the combination of a casing having a lower portion converging to an outlet, means to supply air to the casing to form a vortex, a scroll casing on the casing over the outlet, and a deflecting surface in the bottom of the said scroll casing, converging upwardly into, and centrally of the said outlet, for exhausting the dried material from the casing without substantially disturbing the vortex therein.

9. A drying apparatus for removing moisture from atomized particles, comprising a casing hav-' ing an opening in the top'therecf, means in the opening to introduce atomized fluid into the casing, means to supply a rotating column of heated air to the said opening in the direction of flow of the atomized fluid to form a vortex in the casing, means in the casing forming a slot therein, means to supply heatedair inwardly andoff a tangent of the periphery of the casing through the slot into the casing, means forming a second slot in the casing, means to supply cold air inwardly and off a tangent of the periphery of the casing through the said second slot into the said casing, and means in the lower portion of the casing forming a passage converging to an outlet for exhausting dried material without substantially disturbing the vortex, whereby the vortex may be maintained centrally in the casing, and spaced from the casing walls, throughout its entire length.

10. A drying apparatus for removing moisture from atomized particles, comprising a casing, a cover on the casing having a downwardly converging opening therein, a scroll casing over the opening, an atomizer in the scroll casing extending into and centrally of the said opening forming an annular inlet for introducing a rotating column of heated air to the casing to form a vortex, means forming a tapered slot in the easing, a scroll casing over the slot for directing heated air inwardly and ofi a tangent of the periphery of the casing therethrough into the casing, means in the casing forming a second tapered slot, a scroll casing over the second tapered slot for directing cold air inwardly and off a tangent of the periphery of the casing therethrough to the casing, means in the lower portion of the casing forming a downwardly converging outlet, and a scroll casing on the outlet having a deflecting surface on the bottom thereof converging upwardly into and centrally of the said last outlet for exhausting dried material without substantially disturbing the vortex, whereby the vortex may be maintained centrally in the casing throughout its entire length.

11. In a drying apparatus for removing moisture from atomized particles, the combination of a casing, means forming a plurality of tapered slots in and extending substantially around the periphery of the casing, and scroll casings over the said tapered slots for introducing air inwardly and off a tangent of the periphery of the casing into the casing.

12. In a drying apparatus for removing moisture from atomized particles, the combination of a casing having a lower portion converging to an outlet, means to supply air to the casing to form a vortex; scroll means for exhausting air and dried material outwardly from the casing, and deflecting means cooperating with the said outlet to maintain the characteristic flow, directing the suspended dried material to the said scroll means without substantially disturbing the vortex therein.

13. In a drying apparatus for removing moisture from atomized particles, the combination of a casing having a lower portion converging to an outlet, means to supply air to the casing to form a vortex, scroll means coaxially disposed about the casing, the said outlet extending downwardly into the said scroll means and centrally thereof to cooperate with the said scroll means in exhausting air and dried material outwardly from the casing without disturbing the vortex therein.

WILLIAM SPENCER BOWEN. 

